This invention relates to an automatic focusing device for a cine camera or the like in which the lens is moved to a focused position with the aid of range finding signals that the lens is continuously in focused condition.
An example of a focusing system to which the improvement according to the invention is applicable is shown in U.S. Pat. No. 4,251,145 to Cocron, et al.
In general, an automatic focusing device of this type employs a motor to move the photographing lens to the optimum focused position and the speed of the motor is controlled by varying an electrical energization percentage for the motor, i.e. an energization pulse width.
Heretofore, the pulse width is determined according to the amount of shift of the lens. However, if the lens is moved to the focusing position at a predetermined rate irrespective of the depth of field in the photographing operation, then the resultant picture is unsatisfactory.